RU2782486C1 - Adapter of the osseointegrative system for hip exoprosthesis - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine. The adapter of the osseointegrative system for hip exoprosthesis comprises a body with a blind hole for connecting the implant and a pyramidal adapter for connecting with the exoprosthesis. The adapter has four modules - a locking module, a module to prevent excessive torsional loads on the implant, a module to prevent excessive bending loads and a module for damping shock loads when walking, which are located inside the body one above the other. The body consists of proximal and distal parts connected by an axis of rotation, which works along the axis of flexion of the knee joint and is a cylindrical hinge with a rotation amplitude of 60 degrees. A protrusion is made in the proximal part of the body from below, and a counter part for the proximal part protrusion is made in the distal part from above, while recesses are made on the outer surface of the protrusion. A groove is made in the walls of the blind hole. The pyramidal adapter for connection with the exoprosthesis is made on the lower surface of the distal part of the body on the side of the connection with the prosthesis. The lock module consists of a lock for axial fixation of the implant in the body, set screws, springs and adjusting screws for the springs. The lock for axial fixation of the implant in the body contains an outer bracket, parallel grooves and a cylindrical slot. The rounded part of the slot coincides in diameter with the aforementioned blind hole. The outer pressure bracket has the possibility of exit from the said groove in the wall of the blind hole. The body of the lock with the rounded part of the slot has the possibility of entering the circular groove of the distal part of the implant with the restriction of axial translational movements, with the possibility of axial rotational movements of the implant, relative to the body. The lock for axial fixation of the implant has the possibility of translational movement, the course of which is limited by the set screws, the latter are installed in the proximal part of the body and pass into the parallel grooves of the lock with the possibility of fixing the implant in the body or the absence of such fixation in the extreme positions of the lock travel. The springs of the lock are made opposite the bracket and provide permanent fixation of the distal end of the implant in the body, and when the outer bracket is pressed, they separate the implant and the adapter. The module for preventing excessive torsional loads on the implant is located in the proximal part of the body and consists of an implant cup, stops, springs and screws. The glass is located in the lower part of the said blind hole with the possibility of forming a cylindrical hinge operating in the vertical axis. On the outer contour of the cup, recesses are made for the entry of six stops, spring-loaded by six springs and closed with set screws with the possibility of tensioning the springs and fixing the rotation of the cup together with the implant. The module for preventing excessive bending loads is located in the distal part of the body and consists of stops, springs and adjusting screws. The stops, spring-loaded with six springs and closed with six set screws, have the ability to enter recesses on the outer surface of the projection of the proximal part of the body to be able to fix the rotation of the hinge of the proximal and distal parts of the body. The module for damping shock loads during walking is located inside the distal part of the body and consists of a spring operating along the vertical axis and a slider. The distal part of the body is made of two parts with a gap and has the ability to move apart and move along its axis.

EFFECT: invention provides damping of impact loads arising from walking, increasing the biomechanical stability of the implant, as well as providing protection against peri-implant fractures arising from excessive loads.

1 cl, 6 dwg

Description

The invention relates to the field of limb prosthetics, namely to devices for fixing exoprostheses to the human body and is intended to reduce unwanted loads on the hip exoprosthesis system

Limb exoprosthesis using osseointegration is a relatively new alternative to a prosthetic socket. Its main idea is to use the internal fixation of the exoprosthesis components to the residual bones of the stump using a specialized implant that is connected to the external module of the exoprosthesis outside the human body.

With this approach, an implant is implanted intramedullary into the residual bone of the stump. It emerges percutaneously from the end of the stump, where it is rigidly fixed in the femur by means of osseointegration, and an external prosthesis is attached to its distal end.

The direct connection of an implant with an external prosthesis carries a high risk of complications, such as: biomechanical instability of the implant due to cyclic shock loads when walking due to the fact that the damper systems of standard prostheses are designed to be used in conjunction with a prosthetic sleeve, and not with an implant integrated into the bone ; periprosthetic fractures due to the fact that the implant material is titanium and the stump bone has a significant difference in physical and mechanical properties. These complications can lead to removal of the entire system and shortening of the stump.

Therefore, to connect the implant and the prosthesis, it is necessary to use adapters that protect against excessive loads and provide additional damping of shock cyclic loads when walking.

Known removable attachment system for a prosthetic limb [Releasible attachment system for a prosthetic limb US8246693B2, published 08/21/1912], containing a removable connection system with an osseointegrated part and an external prosthesis, while the attachment system includes a safety release mechanism designed to be released or detached when collision with excessive mechanical load.

The disadvantage of this device is that in case of excessive mechanical load, the external prosthesis will be released or torn off, which is not an intuitive action for a person in critical situations. Releasing or tearing off an artificial limb in critical situations can increase the chance of injury.

Also, the disadvantage of the device is the lack of a mechanism for damping shock loads that occur when walking, which can lead to instability of the implant.

A device for safe overload of a direct skeletal attachment system [“Safety overload for direct skeletal attachment” US 10369028 B2, published on 08/06/2019] is known, containing: a proximal part for attaching to an osseointegrated part; a distal part attached to an external prosthesis; a spring-loaded latch for connecting the proximal and distal parts, released in response to an overload of the prosthetic limb.

The disadvantage of this device is the lack of damping of shock loads that occur when walking, which can lead to failure of the osseointegrated part.

The closest technical solution adopted for the prototype is "Removable attachment system for a prosthetic limb" ["Releasable attachment system for a prosthetic limb" US 20120310371 A1, published 11/06/2012] containing: a connection system with an osseointegrated part and an external prosthesis and a mechanism for preventing excessive loads, formed by a ball joint, where the provision of the threshold for the operation of the device is performed by spring-loaded elements.

The disadvantage of this device is the lack of damping shock loads when walking, which can lead to mechanical instability of the implant.

The objective of the invention is to develop a device that reduces unwanted loads on the hip exoprosthesis system, namely, containing mechanisms for protecting against excessive twisting and bending, as well as a mechanism for damping shock loads that occur when walking, devoid of the above disadvantages.

The result of the invention is achieved due to the fact that the adapter has four modules - a locking module, a module for preventing excessive torsional loads on the implant, a module for preventing excessive bending loads and a module for damping shock loads when walking, which are located inside the housing one above the other, the housing consists of proximal and distal parts interconnected by an axis of rotation that works along the axis of flexion of the knee joint and is a cylindrical hinge with a rotation amplitude of 60 degrees parts, while recesses are made on the outer surface of the protrusion, a groove is made in the walls of the blind hole, a pyramidal adapter for connection with the exoprosthesis is made on the lower surface of the distal part of the body from the side of connection with the prosthesis, the lock module consists of a lock for axial fixation of the implant in the body, set screws, springs and adjusting screws for the springs, the lock for axial fixation of the implant in the body contains an outer bracket, parallel grooves and a cylindrical slot, and the rounded part of the slot coincides in diameter with the aforementioned blind hole, while the outer pressure bracket has the possibility of leaving the said groove in the wall of the blind hole, the lock body with the rounded part of the slot has the possibility of entering the circular groove of the distal part of the implant with the restriction of axial translational movements, if axial rotational movements of the implant are possible, relative to the body, the lock for axial fixation of the implant has the possibility of translational movement, the course of which is limited by set screws, the latter are installed in the proximal part of the body and pass into the parallel grooves of the lock with the possibility of fixing the implant in the body or the absence of such fixation in the extreme positions of the lock travel, the lock springs are made opposite the bracket and provide permanent fixation of the distal end of the implant in the body, and when the outer bracket is pressed, the implant and the adapter are separated, the module to prevent excessive torsional loads on the implant is located in the proximal part of the body and consists of a cup for the implant, stops, springs and screws, the cup is located in the lower part of the mentioned blind hole with the possibility of forming a cylindrical hinge operating in the vertical axis, on the outer contour of the cup there are recesses for the entry of six stops, spring-loaded by six springs and closed with set screws with the possibility of tensioning the springs and fixing the rotation of the cup together with the implant, a module to prevent excessive bending loads is located in the distal part of the body and consists of stops, springs and adjusting screws, and the stops, spring-loaded with six springs and closed with six set screws, have the ability to enter recesses on the outer surface of the high blunt of the proximal part of the body for the possibility of fixing the rotation of the hinge of the proximal and distal parts of the body, the module for damping shock loads when walking is located inside the distal part of the body and consists of a spring operating along the vertical axis and a slider, while the distal part of the body is made of two parts with a gap and has the ability to move apart and move along its axis.

The technical result consists in providing damping of shock loads that occur when walking, increasing the biomechanical stability of the implant, as well as providing protection from peri-implant fractures that occur during excessive loads.

The body of the adapter consists of two parts, forming a cylindrical hinge in the axis of knee flexion, which is a mechanism to prevent excessive bending loads. The hinge has an adjustable load threshold, provided by stops, springs and screws, before reaching which all movements in it are blocked. When excessive load is above a predetermined threshold, the body can fold out in the plane of knee flexion, preventing the occurrence of excessive bending loads in the plane of the knee joint, leading to peri-implant fractures.

The body contains a cup in which the implant is secured with a lock, while the cup and the body form a cylindrical hinge operating in a vertical axis, and this ensures that excessive torsional loads are prevented. The hinge has an adjustable load threshold, provided by stops, springs and screws, before reaching which all movements in it are blocked. When an excessive load exceeds a predetermined threshold, the cup can rotate along with the implant in a vertical axis with respect to the body of the invention, preventing the occurrence of excessive torsional loads leading to peri-implant fractures.

The adapter occupies an important place in the osseointegrative system of hip exoprosthesis, as it performs the function of connecting the implant to the external hip prosthesis and increases the biomechanical stability of the implant by damping axial loads and protecting against periprosthetic fractures. Load damping is ensured by the location of a spring and a slider in the distal part of the body, which operate along the vertical axis and, under load, shift the two parts of the distal part of the body, and when the load is relaxed, they move them apart.

The essence of the invention is illustrated by the following drawings.

In FIG. 1 shows isometric (A) and frontal (B) views of the adapter of the osseointegrative system for hip exoprosthesis.

In FIG. 2 shows an isometric transparent view A and a side view B at the moment of operation of the mechanism of protection against excessive bending loads on the adapter.

In FIG. 3 shows a view of the implant fixation mechanism.

In FIG. 4 shows a sectional view of the mechanism for protecting the system from excessive torsional loads.

In FIG. 5 shows a section of the mechanism for protecting the system from excessive bending loads.

In FIG. 6 shows a general view of the utility model as part of an osseointegrative system for hip exoprosthesis.

The adapter (Fig. 1, 2, 3) consists of a cylindrical body 1 with 1 modules A-G located in it. The body 1 consists of proximal 4 and distal 5 parts, interconnected by an axis of rotation 6, which 6 is a cylindrical hinge with a rotation amplitude of 60 degrees. (Fig. 2b). Axis of rotation 6 works along the axis of flexion of the knee joint. The outer wall of the proximal part 4 at the level of the hinge 6 is beveled at an angle of 60 degrees. The thrust pad on the distal part 5 for the hinge 6 is made perpendicular to the axis of the body 1.

To adapt both parts 4, 5 of the body 1, in the proximal part 4, a protrusion is made from below, and in the distal part 5, a counter part is made from above, in which the mentioned protrusion of the proximal part 4 is installed.

On the upper surface of the proximal part 4 of the body 1, on the side of the connection with the implant, a blind hole 2 is made for adaptation to the distal part of the osseointegrated implant. A groove is made in the walls of the hole 2 for accommodating the inner part of the lock 7 (the rounded part of the slot of the lock 7). The width of the groove of the hole 2 and the thickness of the lock 7 are the same. The diameter of the rounded part of the slot of the lock 7 and the groove of the hole 2 are the same.

A pyramidal adapter 3 is made on the lower surface of the distal part 5 of the body 1 on the side of the connection with the prosthesis.

The proximal part 4 and the distal part 5 of the body 1 are divided into several parts fastened with fasteners to ensure manufacturability and ease of assembly (figure 2, A).

The distal part 5 consists of two parts, with a gap between them.

If we consider the invention systematically, then inside the case 1, one above the other, there are four modules A-G, performing various functions.

Hole 2 is blind and ends in module B. Implant 23 is inserted into hole 2 and fixed in it 2 with lock 7, and an exoprosthesis is attached to the pyramidal adapter 3 (Fig. 6), thereby connecting the implant and the hip exoprosthesis, forming an osseointegrative system hip exoprosthesis. The depth of the hole 2 corresponds to the length of the distal attachment part of the implant 23.

Module A (Fig. 3) consists of lock 7, set screws 8, springs 9 and set screws 10. Lock 7 contains a cylindrical slot, and the rounded part of the slot coincides in diameter with hole 2 and enters its 2 groove. The lock 7 is a reciprocating link and is designed for axial fixation of the implant in the body 1 and having a stroke of 2 mm, which is limited by the set screws 8. The screws 8 are installed in the proximal part 4 of the body 1 and pass 8 into the parallel grooves of the lock 7, the length of the lock grooves 7 is equal to 2 mm. In the distal part of the implant 23, a circular groove is made, into which the body of the lock 7 enters with the rounded part of the slot, limiting axial translational movements, but allowing axial rotational movements of the implant relative to the body 1, due to the fact that the body of the lock 7 comes into contact with the circular groove of only the upper and bottom surface. In the extreme positions of the course of the lock 7, it 7 either fixes the implant in the housing 1 or not. The lock 7 is spring-loaded by three springs 9, the tension force of which is regulated by set screws 10. The springs 9 of the lock 7 are made opposite the bracket 11.

At the level of the lock 7 in the wall of the proximal part 4 of the body 1, a groove is made for the exit of the outer part of the lock 7 - its bracket 11.

Module B is located in the proximal part 4 of the housing 1 and is designed to prevent excessive torsional loads on the implant. The mechanism B consists of a glass 12, stops 13, springs 14 and screws 15. The glass 12 is located at the bottom (in the lower part) of the blind hole 2 and they 2, 12 together form a cylindrical hinge operating in the vertical axis. When the implant is connected to the adapter, the implant is fixed in the cup 12, due to the lock 7, module A, after which it can only rotate together with the cup 12. Under excessive load, the cup 12 rotates in the vertical axis relative to the proximal part 4 of the body 1 (figure 4).

On the outer contour of the cup 12, recesses are made, where six stops 13 go, spring-loaded with six springs 14 and closed with six set screws 15, providing spring tension and fixing the rotation of the cup 12 together with the implant under normal loads

Module B is located in the distal part 5 of body 1 and is designed to prevent excessive bending loads.

Module B consists of stops 16, springs 17 and screws 18.

The stops 16, spring-loaded by six springs 17 and closed by six set screws 18, enter the recesses on the outer surface of the projection of the proximal part 4 of the body 1, ensuring that the rotation of the hinge 6 of the proximal 4 and distal 5 parts of the body 1 is fixed under normal loads.

Module G (Fig. 5) is also located inside the distal part 5 of the body 1 and is designed to dampen shock loads that occur when walking. Module G consists of a spring 20 operating along the vertical axis and a slider. Together with the spring, the damping function is also ensured by the fact that the distal part 5 of the body 1 can be moved apart and shifted by 2 mm along its axis (Fig. 1, B, 19) due to the slider 25 installed inside (Fig. 1).

The pyramidal adapter 3 is connected to the distal part 5 of the body 1 by a splined connection, which is engaged by a screw 21. If necessary, the pyramidal adapter 3 can be rotated along its axis when the screw 21 is loosened. Its rotation ensures a change in the angle of the prosthesis foot relative to the patient.

As part of the osseointegrative hip exoprosthesis system, the adapter connects the implant 23 implanted in the stump 22 with the exoprosthesis 24 (Fig. 6).

The adapter works like this:

To connect the adapter with the implant implanted in the stump (Fig. 6, 22), the implant is inserted into the proximal hole 2. The lock 7 blocks the axial movement of the implant 23, but not the rotation (the rotation of the implant is blocked by the cup 12). The lock 7 is spring-loaded by three springs 9, the tension force of which ensures the permanent fixation of the distal end of the implant 23 in the housing 1 (Fig. 3). First, the bracket 11 of the lock 7 is pressed, thereby shifting the lock 7, the distal end of the implant 23 is inserted so that it reaches the bottom of the cup 12, then the bracket 11 is released and the force of the springs 9, part of the body of the lock 7 enters the circular groove of the implant 23, which fixes its 23 from translational axial movements.

If it is necessary to disconnect the implant 23 and the adapter, it is necessary to press the bracket 11 of the lock 7, thereby shifting the lock 7 perpendicular to the axis (Fig. 3, 11) of the implant 23, and separate the adapter and the implant 23.

External prosthesis 26 (Fig. 6) is attached to the pyramidal adapter 3 (Fig. 1) by fixing it in the standard connector of the pyramidal adapter.

When using the adapter for the first time, adjust the position of the pyramidal adapter 3, for this, loosen the screw 21, then turn the pyramidal adapter to the desired position, then tighten the screw 21.

Once assembled (FIG. 6), the patient can use the prosthesis for walking.

During walking in the phase of the impact of the heel on the surface (Fig. 1, B), the distal part 5 of the body 1 is compressed 19 by 2 mm, while the spring 20 is compressed, damping the patient's step. When the load is removed at the moment of the leg transfer phase, the distal part 5 of the body 1 moves apart 19 by 2 mm, the spring 20 is released, after which the damping can be repeated.

To ensure adequate operation of the protection mechanisms of modules B and C, depending on the weight of the patient and his level of activity, the thresholds for the operation of protection systems against excessive loads are adjusted. To do this, in module B, the depth of screws 15 is adjusted, and in module C, screws 18. When the screws are screwed, the springs of the mechanisms are compressed more and more, increasing the threshold of the system.

After adjusting the response threshold, a series of tests are carried out to determine the normal operation of the adapter. Modules B and C should not operate during normal physical activity of the patient.

In extreme cases, with excessive twisting of the implant 23, the springs 14 lack the force of pressing the stops 13 against the recesses in the cup 12 to prevent the cup 12 from turning (Fig. 4). Cup 12 with implant 23 installed in it rotates around its axis (Fig. 4), pushing spring-loaded stops 13 out of the recesses, thereby compressing springs 14. Turning cup 12 relieves stress on the osseointegrated part.

In extreme cases, with excessive bending in the plane of flexion of the knee joint, the springs 17 lack the force of pressing the stops 16 to the recesses in the ledge of the proximal part 4 of the body 1 to keep the proximal 4 and distal 5 parts of the body 1 stationary relative to each other. As a result, the proximal part 4 of the body 1 rotates relative to the distal part 5 of the body 1 along the axis 6 (Fig. 2, B, 15), pushing the stops 16, compressing the springs 17, the outer wall of the proximal part 4 at the level of the hinge 6 rests against the thrust pad on the distal part 5, thereby preventing the occurrence of excessive loads of this type.

Claims (1)

An adapter for an osseointegrative system for hip exoprosthesis, containing a body with a blind hole for connecting an implant and a pyramidal adapter for connecting with an exoprosthesis, characterized in that the adapter has four modules - a locking module, a module to prevent excessive torsional loads on the implant, a module to prevent excessive bending loads, and module for damping shock loads during walking, which are located inside the body one above the other, the body consists of proximal and distal parts connected by an axis of rotation, which works along the axis of flexion of the knee joint and is a cylindrical hinge with a rotation amplitude of 60 degrees, in the proximal a protrusion is made on the bottom of the housing part, and a counter part for the proximal part protrusion is made on the top, while recesses are made on the outer surface of the protrusion, a groove is made in the walls of the blind hole, a pyramidal adapter for connecting with e the prosthesis is made on the lower surface of the distal part of the body from the side of connection with the prosthesis, the lock module consists of a lock for axial fixation of the implant in the body, set screws, springs and adjusting screws for springs, the lock for axial fixation of the implant in the body contains an external bracket, parallel grooves and a cylindrical slot, and the rounded part of the slot coincides in diameter with the mentioned blind hole, while the outer pressure bracket has the ability to exit the mentioned groove in the wall of the blind hole, the lock body with the rounded part of the slot has the ability to enter the circular groove of the distal part of the implant with limitation of axial translational movements , with the possibility of axial rotational movements of the implant relative to the body, the lock for axial fixation of the implant has the possibility of translational movement, the course of which is limited by the set screws, the latter are installed in the proximal part of the body and pass into the parallel grooves of the lock with the possibility of fixing the implant in the body or the absence of such fixation in the extreme positions of the lock travel, the lock springs are made opposite the bracket and provide permanent fixation of the distal end of the implant in the body, and when the outer bracket is pressed, they ensure the separation of the implant and the adapter, a module to prevent excessive torsional loads on the implant is located in the proximal part of the body and consists of a cup for the implant, stops, springs and screws, the cup is located in the lower part of the said blind hole with the possibility of forming a cylindrical hinge operating in the vertical axis, recesses are made on the outer contour of the cup for the entry of six spring-loaded stops six springs and closed set screws with the possibility of tensioning the springs and fixing the rotation of the cup together with the implant, the module to prevent excessive bending loads is located in the distal part of the body and consists of stops, springs and adjusting screws, with than the stops, spring-loaded with six springs and closed with six set screws, have the ability to enter the recesses on the outer surface of the protrusion of the proximal part of the body for the possibility of fixing the rotation of the hinge of the proximal and distal parts of the body, the module for damping shock loads when walking is located inside the distal part of the body and consists of a spring operating along the vertical axis, and a slider, while the distal part of the body is made of two parts with a gap and has the ability to move apart and move along its axis.

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